Phthalate esters are widespread contaminants that can cause endocrine disruption in vertebrates. Studies showed that molecules with hormonal activities in vertebrates and invertebrates can affect asexual ... [more ▼]

Phthalate esters are widespread contaminants that can cause endocrine disruption in vertebrates. Studies showed that molecules with hormonal activities in vertebrates and invertebrates can affect asexual and sexual reproduction in rotifers. We investigated the impact of di-hexylethyl phthalate (DEHP), di-butyl phthalate (DBP) and butylbenzyl phthalate (BBP), on the asexual and sexual reproduction of the freshwater monogonont rotifer Brachionus calyciflorus in order to determine a potential environmental risk for sexual reproduction. We observed that DEHP has no significant impact on both asexual and sexual reproduction up to 2 mg/L. DBP has a positive effect on asexual reproduction at concentrations from 0.05 to 1mg/L, but depresses it at 2 mg/L. Sexual reproduction is only affected with 2mg/L and the impact observed is negative. BBP displayed a negative impact on both asexual and sexual reproduction at 1 and 2 mg/L. However we showed that the impacts of BBP on fertilization rates observed are due to the decrease in population growth rates at these concentrations and are not due to a direct impact of BBP on the fertilization process. Similar conclusions are likely applicable to the impacts on mixis and production of cysts as well. Our results show that sexual reproduction in B. calyciflorus is not more sensitive than asexual reproduction to any of the substances tested which indicates the mode of action of these molecules is related to general toxicity, not to an interference with potential endocrine regulation of sexual reproduction. Comparison of effect concentrations and surface water contamination by phthalate esters suggests these compounds do not constitute a risk for these environments. [less ▲]

Several studies have shown that pollutants with anti-androgenic activity have an impact on the sexual reproduction of the rotifer Brachionus calyciflorus (Joaquim-Justo et al., submit; Preston et al ... [more ▼]

Several studies have shown that pollutants with anti-androgenic activity have an impact on the sexual reproduction of the rotifer Brachionus calyciflorus (Joaquim-Justo et al., submit; Preston et al., 2001). The effects observed are compatible with the phenomenon of endocrine disruption. Fenitrothion, a non-steroidal anti-androgen induces a decrease in fertilization rate following exposure below or equal to 0,5 mg L-1.. The steroidal anti-androgen, cyproterone acetate increases number of cysts in population exposed to concentrations below or equal to 0,5 mg L-1. Cross mating experiments showed that effects of fenitrothion are due to an impact on males exclusively, while effects of cyproterone acetate exposition are due to an impact on females exclusively. In this study, we investigated the impact of fenitrothion on spermatogenesis and observed a decrease in the spermatozoa production and mobility with concentrations down to 0,5 mg L-1. We report a detailed description of the morphology of the male reproductive apparatus in B. calyciflorus based on optic, transmission electron and scanning electron microscopy in controls and exposed individuals. [less ▲]

Putative endocrine disruptors affect rate of fertilization of sexual females by males. Preston et al. (2000) reported a decrease in fertilization rate following exposition to, notably, flutamide at 10µg/l. We observed similar effects with fenitrothion. Cross mating experiments showed that the decrease in fertilization rate is due to an impact on males exclusively. We studied the impact of anti-androgens on spermatogenesis and observed a decrease in the spermatozoa production with concentrations down to 0,5 mg L-1.We also report a detailed description of the morphology of the male reproductive apparatus in B. calyciflorus based on optic and electronic microscopy analysis and we describe the effect of anti-androgens on males and spermatogenesis in males. [less ▲]